<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<script>
			var a,b;
			(function(){
			    alert(a);
			    alert(b);
			    var a=b=3;
			    alert(a);
			    alert(b);
			})();
			alert(a);
			alert(b);
		</script>
	</head>
	<body>
		
	</body>
</html>
